New Cogeneration Plant Helps Spanish Refinery Meet Growing Power And Steam Needs. gas turbine technology to boost output and efficiency, lower emissions
To help meet a growing demand in Europe for middle distillates such as diesel fuel and kerosene, Compañia Española de Petróleos S.A. (CEPSA) is expanding the capacity of its La Rábida refinery in Huelva, Spain.
Based in Madrid, Spain, CEPSA is one of the leading companies in Spain’s petrochemical and petroleum sector. Its three refineries account for one-third of the country’s total refining capacity. The La Rábida refinery expansion, which is expected to increase refining capacity from 5 million to 9 million tons per year in order to meet gas oil demand, will require additional process steam and electricity. To help meet that need, CEPSA is building a new cogeneration plant at the site. Using technology supplied by GE, the plant will increase the output and the efficiency of power and steam production While also reducing the environmental impact of the entire refinery.
Cogeneration (also combined heat and power, CHP) is the use of a heat engine or a power station to simultaneously generate both electricity and useful heat. It is one of the most common forms of energy recycling. The heart of the new cogeneration plant is a GE Frame 6FA gas turbine-generator, equipped with an advanced dry-low NOx (DLN) combustion system for operation on natural gas. The La Rábida unit is the 15th frame 6FA to be supplied for power generation or industrial applications in Spain, and the 12th installed in a refinery worldwide. The plant also includes a 9 MW Thermodyn steam turbine delivered by GE Oil & Gas.
All CEPSA GE gas turbines are served under a multiyear maintenance plan. This project marks the first time that CEPSA has selected a high efficiency F-class gas turbine (with an output greater than 50 MW and sub-15 parts per million [ppm] NOx) for a Cogeneration application. Historically, turbines with outputs below 50 MW and NOx emissions levels below 25 ppm have been used. For example, a 40 MW GE Frame 6B gas turbine has been running in cogeneration mode at the CEPSA site since 1990. Overall, CEPSA has 20 years of experience with cogeneration applications.
Spain’s latest Royal Decree for Renewables and Cogeneration, enacted in 2007, allows cogeneration plants to surpass the former 50 MW limit and still qualify for the country’s
feed-in tariff for the first 50 MW. This enables the use of GE 6FA technology
to meet CEPSA’s requirements for higher energy output The midsized member of GE’s family of advanced F-class gas turbines, the Frame 6FA, was scaled down in the 1990s
from the well-proven GE Frame 7FA gas turbine. It has sold more than 110 units and has logged more than 2.9 million operating hours in various industrial and power plant environments.
The 6FA is capable of producing more than 75 MW of power in simple-cycle service, and 118 MW at 54.7% efficiency in combined cycle. Its output range, high exhaust energy (135 MWth), compact and robust design make the machine well suited for industrial applications such as cogeneration, according to GE.
The exhaust flow of the Frame 6FA at around 600°C allows generation of steam at high pressure to meet the industrial needs of the La Rábida site, while the machine’s shaft efficiently produces electricity that is sold to the Spanish power grid. The plant has a low consumption of about 1 MWh, compared to an estimated export of electricity of around 80 MWh, based on the plant design. The modular design of the 6FA provides layout flexibility for ease of commissioning and maintenance. It is equipped with a triple modular redundancy Mark Vle control system, for easy integration into the La Rábida plant’s distributed control system.
The 6FA at La Rábida features GE’s advanced, DLN 2.6 combustion system, which has the capability to reduce nitrous oxide (NOx) emissions to 15 ppm or less. Thanks to this extension, the total refinery emission reductions are 10% in SO2, 9% in NOx and 5% in particles. The DLN 2.6 technology is capable of reducing combined-cycle emissions without the use of any water, chemical or catalytic system. In addition to reducing emissions, The technology also enables the gas turbine to be operated at lower power during off-peak periods, consuming less fuel and helping to reduce plant operating costs. This enhanced product builds upon decades of GE experience in combustion technology.
“We turned to advanced gas turbine technology for the expansion of our cogeneration plant to meet our increased demand for process steam and electricity with a high fuel savings, compared to a conventional boiler,” said R. Moreno Lahore, head of the power plant for CEPSA. “Also, we were interested in a good return on investment (depending on natural gas and power prices) and the higher efficiency of the 6FA technology is a key to meeting that goal.
“The new plant is designed for this gas turbine. The turbine’s performance (exhaust temperature and flow) enables the plant to meet steam demand without post combustion, with a very high efficiency. Another key factor in our selection of 6FA technology is its proven track record in refineries and other industrial applications worldwide,” he added.
Construction of the cogeneration plant expansion is nearly completed, with full commercial service expected to begin in Q1 2011.